Current approaches to quantifying audibility and predicting speech recognition for children are based on adult data, and consequently, overestimate performance for children and underestimate the amount of audibility that is necessary to achieve high levels of understanding. Although differences in speech recognition between adults and children have been widely studied, lack of research examining how such differences impact audibility-based predictions of speech recognition limits the clinical application of these findings. Furthermore, the accuracy of such predictions with children is presently inadequate. The long-term goal of this research is to enhance speech and language outcomes in children with HL by improving Speech Intelligibility Index (SII) predictions of speech recognition. More accurate estimates of speech recognition would promote optimization of amplification for children. An intermediate objective is to quantify the influence of language and immediate memory on predictions of speech recognition from the SII. To achieve this objective, speech recognition, receptive language, and immediate memory skills will be measured in children and used to generate transfer functions. The central hypothesis of this proposal is that adult-child differences and variability among children can be more accurately predicted by modifying the SII to account for children's linguistic ability and immediate memory, a hypothesis that is supported by preliminary data. This theory will be tested by pursuing three specific aims: 1) Determine the influence of linguistic abilities on audibility-based predictions of speech recognition in children with normal hearing (NH), 2) Determine the influence of immediate memory processes on audibility-based predictions of speech recognition in children with NH, and 3) Adapt the SII to more accurately predict speech recognition in children with HL by incorporating linguistic knowledge and immediate memory skills. In Aim 1, speech recognition and language abilities will be measured for a large group of children with normal hearing in order to determine if consideration of the listener's language knowledge can improve SII predictions of speech recognition. In Aim 2, speech recognition and immediate memory skills, including verbal and visuo-spatial measures of storage and storage with processing, will be measured for a large group of children with normal hearing to determine how these processes support speech recognition. In Aim 3, measures of language and immediate memory will be incorporated into SII transfer functions for a group of children with hearing loss to model how these factors affect unaided and aided speech understanding. The proposed research is expected to lead to optimization of amplification in children with hearing loss and a better understanding of how language and immediate memory influence speech recognition during development.